U.S. patent number 4,145,766 [Application Number 05/859,893] was granted by the patent office on 1979-03-27 for adjustable friction joint for an artificial knee.
This patent grant is currently assigned to J. E. Hanger & Company Limited. Invention is credited to Denis R. W. May.
United States Patent |
4,145,766 |
May |
March 27, 1979 |
Adjustable friction joint for an artificial knee
Abstract
The angular movement of a knee joint of the kind comprising a
four bar linkage is controlled by the frictional engagement of a
shaft, pivoted at one end to one of the links, with a pivotable
plastics bush located between the ends of another link. The
plastics bush may be tightened around the shaft to adjust the
frictional restraint on the movement of the joint.
Inventors: |
May; Denis R. W. (London,
GB2) |
Assignee: |
J. E. Hanger & Company
Limited (London, GB2)
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Family
ID: |
10463353 |
Appl.
No.: |
05/859,893 |
Filed: |
December 12, 1977 |
Foreign Application Priority Data
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Dec 15, 1976 [GB] |
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52287/76 |
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Current U.S.
Class: |
623/45;
623/39 |
Current CPC
Class: |
A61F
2/644 (20130101); A61F 2/68 (20130101) |
Current International
Class: |
A61F
2/60 (20060101); A61F 2/64 (20060101); A61F
2/68 (20060101); A61F 2/50 (20060101); A61F
001/08 () |
Field of
Search: |
;3/28,26,22,27 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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2332993 |
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Jan 1975 |
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DE |
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810752 |
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Jan 1937 |
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FR |
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Primary Examiner: Crowder; Clifford D.
Attorney, Agent or Firm: Pollock, VandeSande and Priddy
Claims
I claim:
1. In a knee joint comprising a four-bar linkage of which two links
are connected to a shin portion and a thigh portion respectively,
said shin and thigh portions forming the other two links, the
improvement comprising a shaft pivotally connected at one end to
one link of said four-bar linkage, and a plastics bush pivoted to
another link of said four-bar linkage, said shaft passing through
said plastics bush in frictional engagement therewith whereby
angular movement of the knee joint is controlled.
2. A knee joint comprising a thigh portion, a shin portion, a front
link pivotably connected to the thigh and shin portions and a rear
link pivotably connected to the thigh and shin portions and
completing a four-bar linkage, a shaft pivoted at one end about the
pivotal axis connecting two links of said four-bar linkage and a
plastics bush pivotable about an axis located between the ends of
another bar of said linkage, said shaft passing through and
frictionally engaging said plastics bush.
3. A knee joint as described in claim 2, wherein said shaft is
pivotable about the axis of the pivotal connection between said
rear link and said thigh portion and said plastics bush is pivoted
to said shin portion between said front and rear links.
4. A knee joint as described in claim 2, including means for
adjusting the frictional engagement of said plastics bush with said
shaft.
5. A knee joint as described in claim 4, wherein said means
comprises a screw traversing a longitudinal slot in said bush and
threadable into said bush to very the tightness of said bush on
said shaft.
Description
BACKGROUND OF THE INVENTION
This invention is concerned with artificial legs and more
particularly with the knee joints of such legs.
A known type of knee joint comprises a four-bar linkage, two of the
links being adapted for conection to a shin portion and a thigh
portion respectively and being connected by the other two links.
The linkage may be designed so that in bending the knee, there is
an initial resistance to angular movement over a predetermined
angle followed by substantially free movement to the fully bent
position.
An object of the present invention is to control the angular
movement of a knee joint of this kind by introducing a frictional
restraint on the movement of the links.
PRIOR ART
The most relevant prior art known to the Applicant in U.S. Pat. No.
3,823,424.
SUMMARY OF THE INVENTION
From one aspect, the invention provides a knee joint of the kind
referred to including a shaft pivotably connected at one end to one
of the links of the four-bar linkage and slidable through a
plastics bush pivoted to another link of said linkage. Preferably
the shaft is pivotable to the bar formed by the thigh portion and
slides through a bush pivoted to the shin portion which forms the
other bar.
From another aspect, the invention provides a knee joint of the
kind referred to having a shaft pivoted at one end about the
pivotal axis connecting two bars of the linkage and slidable
through a plastics bush pivotable about an axis situated between
the ends of another bar of the linkage.
The plastics bush may have a longitudinal slot and may be tightened
around the shaft to control the friction therewith by a screw
passing transversely of the slot.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side view of one embodiment of the invention;
FIG. 2 is a section on the line A--A of FIG. 1; and
FIG. 3 is a section on the line C--C of FIG. 1.
DESCRIPTION OF A PREFERRED FORM
Referring to the drawings, a knee joint comrises a thigh part 1
adapted for connection to a member 2 forming the thigh of the
artificial leg, and a shin part 3 adapted for connection to a
member 4 forming the shin of the leg. The thigh part 1 and the shin
part 3 are pivotally connected to opposite ends of a front link 5
by pivots 6, 7 respectively and to opposite ends of a rear link 8
by pivots 9, 10 respectively. The thigh part 1, front link 5, shin
part 3 and rear link 8 form a four-bar chain which may be designed
so that there is an initial resistance to relative movement of the
thigh and shin over a small angle followed by substantially free
movement until the leg is fully bent.
A shaft 11 is pivotably mounted at one end about the axis of the
pivot 9 connecting the upper end of the rear link 8 with the thigh
part 1. A tube 12 coaxial with the pivot 9 is mounted in the thigh
part 1 and passes through a hole in the enlarged end 13 of the
shaft 11, the thigh part having a recess 14 to accommodate the end
13.
The other end of the shaft 11 passes through a plastics bush 15 and
is a slidable fit therein. This bush 15 is pivotably mounted on the
shin part 3 midway between the pivotal connections 7, 10 of the
front and rear links 5, 8. A cylindrical recess 16 to receive the
bush 15 is formed in the top of the shin part 3 and pins 17, 18
project into this recess to form bearings for the bush 15. The
inner ends of the pins 17, 18 are spaced apart to allow passage
between them of the shaft 11.
The bush 15 is split longitudinally on one side and a screw 19
connects the portions of the bush on opposite sides of the split.
The screw 19 may be threaded in or out to tighten or loosen the
bush around the shaft 11 and thereby increase the friction between
them.
It will be seen that as the knee joint is bent, the shaft 11 slides
through the bush 15 against the frictional force therebetween so
that the movement of the joint is controlled. Adjustment of the
controlling force is afforded by tightening the bush around the
shaft.
It will be understood that the invention is not restricted to the
details of the preferred form described by way of example which may
be modified without departure from the scope of the accompanying
claims.
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